1. Field of the Invention
The present invention relates to improvements in AC plasma display panels, and more particularly to an AC plasma display panel (referred to hereinafter as xe2x80x9cAC PDPxe2x80x9d) which comprises a rear substrate formed with separated sub-pixel spaces defined thereon by closed shape barrier ribs for forming color pixels respectively composed of three sub-pixels of red, green and blue phosphor layers disposed in a delta configuration in those sub-pixel spaces, and a front substrate formed with sustain electrodes having projections or wings respectively sticking out or extended over each sub-pixel to face a wing of the neighboring sustain electrode thereby achieving improved absolute luminance and luminous efficiency at the same time.
2. Description of the Prior Art
As well known to those skilled in the art, there have been developed a variety of AC PDPs having diagonal sizes that range from about 40 inches to about 60 inches. Where high resolution is to be achieved as in an XGA class AC PDP having 1024xc3x97768 pixels, the size of a color pixel shall become smaller than 1 mm2, which requires the effective utilization of its discharge volume. Accordingly, it is essential to develop an AC PDP that has an excellent luminous efficiency by modeling the optimized construction of barrier ribs and the suitable sustain electrodes.
FIG. 1 is a perspective view showing the construction of a conventional AC PDP.
The conventional AC PDP comprises a rear substrate 1 having a dielectric layer 2, a plurality of stripe-structured barrier ribs 141 to 14n formed on the dielectric layer to create channels therebetween, a plurality of address electrodes 151 to 15n embedded in the dielectric layer 2 while being arranged in parallel and regularly spaced apart from each other and a plurality of red, green and blue phosphor layers 11, 12 and 13 alternately disposed on the surface of the channels between the barrier ribs 141 to 14n to create RGB sub-pixels, and a front substrate 3 covering the rear, substrate 1 having sustain electrodes 71 to 7n arranged in parallel to each other and perpendicularly to the respective barrier ribs 141 to 14n and spaced regularly apart from each other, bus electrodes 6 disposed outside the sustain electrodes 71 to 7n, black stripes 8 disposed outside the bus electrodes 6, and a protective layer 10, all of which are formed on its inner surface.
In such an AC PDP, the electric discharges of the sustain electrodes 71, . . . , or 7n generate ultraviolet light, which excites the corresponding phosphor layer to emit visible light, and thus the visible light is seen through the front substrate 3. As depicted in FIG. 1, the RGB sub-pixels are divided into groups of color pixels of the RGB sub-pixel sets.
In brief, in that conventional AC PDP, the address electrodes 151 to 15n are arranged between the respective barrier ribs 141 to 14n on the rear substrate to control electric discharges, while the sustain electrodes 71 to 7n are disposed on the front substrate 3 to be perpendicular to the address electrodes 151 to 15n.
Accordingly, this conventional AC PDP has advantages of simple construction of barrier ribs and easy control of discharging in those RGB sub-pixels by using address electrodes.
However, the conventional AC PDP has the disadvantage that the discharge area in a sub-pixel is not effectively utilized because discharges occur only in the center portion of the longish discharge area, having a horizontal width to vertical length ratio of one to three, with the remaining portion being not used.
The Japanese Laid-open Patent Application No. Hei 9-50768 discloses an AC PDP in which a plurality of phosphor-coated sub-pixels are arranged in a delta configuration so as to increase the effective area for luminance. In that AC PDP, meander barrier ribs 181 to 18n are formed, with neighboring barrier ribs 18n and 18n+1 being linearly symmetrical to each to vary periodically in width, thus forming a guasi-honeycomb structure on the whole. A plurality of red, green and blue phosphors R, G and B are respectively disposed in a delta configuration in the wider portions 19 of the channels formed by the meander column barrier ribs 181 to 18n to create RGB sub-pixels.
However, this AC PDP is not so effective in that the construction of sustain electrodes is not adapted to the shape of RGB sub-pixels for preventing erroneous addressing discharge and two barrier ribs exist between neighboring RGB sub-pixels, though the effective area for luminance is increased.
Accordingly, the present invention has been made in consideration of the above problems in the prior art PDPs, and an object of the present invention is to provide an AC PDP with improved absolute luminance and luminous efficiency resulting from new and inventive shapes of the RGB sub-pixels and the sustain electrodes.
Another object of the present invention is to provide an AC PDP, in which absolute luminance and color temperature are improved by designing the size and shape of the sustain electrode corresponding to the kinds of phosphors of the respective sub-pixels.
In order to accomplish the above objects and others, the present invention provides an AC PDP, comprising: a rear substrate formed with sub-pixel spaces defined by closed shape barrier ribs for forming color pixels respectively composed of three pixels of red, green and blue phosphor layers disposed in those sub-pixel spaces in a delta configuration and correspondingly designated address electrodes, and a front substrate formed with sustain electrodes having projections or wings respectively extended or sticking out over each subpixel to face a projection or wing of the neighboring sustain electrode.
According to an aspect of the present invention, the length of the projected wing portion of each sustain electrode is within a range of xc2xd to ⅔ of the length of the respective phosphor-coated sub-pixel region, resulting in optimization of luminous characteristics and discharging capabilities.
According to another aspect of the present invention, each sustain electrode has T-shaped wings, resulting in reduction of the size of the electrode with the length of the part of the electrode for discharging being maintained and the absolute luminous efficiency being improved.
According to still another aspect of the present invention, a sustain electrode may be formed by being laterally extended from an opaque rectangular bus electrode with the thickness of around 40 xcexcm for improving absolute luminous efficiency.
According to yet another aspect of the present invention, the width of the sub-pixels with the blue phosphor layer is broader than the neighboring sub-pixels with the red phosphor layer, or the lengths of the sustain electrodes vary depending on the kinds of the phosphors coated in the respective sub-pixels, thereby solving the problem that an additional compensation is required for the color temperature which is lowered as white color is tinged with red color owing to the influence of orange color emitted from neon gas and the relatively low luminous efficiency of blue phosphors and the high reduction rate of luminance due to deterioration of the blue phosphors.